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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Collinear ferromagnetism with reduced moment length in kagome magnet Nd 3 ⁢Ru 4 ⁢Al 12

Here, we determine the magnetic ground state of the kagome lattice magnet Nd 3 ⁢Ru 4⁢ Al 12 by single-crystal neutron diffraction, supported by experiments with polarized neutrons. We identify this material as a collinear ferromagnet (“hex-FM”) with uniform moment length and ordering vector 𝑸 = 0, in contrast to a previous, seminal report that proposed unequal moment lengths on two Nd sites, here called the “ortho-FM” state. Our analysis of the flipping ratio in polarized neutron scattering is consistent with the hex-FM state. The results provide a microscopic basis for understanding the large fluctuation-induced Hall and Nernst responses near 𝑇 C ≈ 41K, as previously reported for Nd 3 ⁢Ru 4 ⁢Al 12 .

RKKY interaction↗
DOE OSTI2020

Cooperative Ru(4 d )–Ho(4 f ) magnetic ordering and phase coexistence in the 6 H perovskite multiferroic Ba 3 HoRu 2 O 9

We report cooperative magnetic orderings in a 6H-perovskite multiferroic system, Ba 3 HoRu 2 O 9 , via comprehensive neutron powder diffraction measurements. This system undergoes long-range antiferromagnetic ordering at T N1 ~ 50 K with a propagation wave vector of K 1 = (0.5 0 0), a transition temperature much higher than the previously reported one at ~10 K (T N2 ). Both Ru and Ho-moments order simultaneously below T N1 , followed by spin-reorientations at lower temperatures, demonstrating strong Ru(4d)-Ho(4f) magnetic correlation. Below T N1 another magnetic phase with a propagation wave vector K 2 = (0.25 0.25 0) emerges and coexists with the one associated with K 1 , which is rarely observed and suggests complex magnetism due to phase competition in the magnetic ground state. Here, we argue that the exchange-striction arising from the up-up-down-down spin structure associated with K 2 below T N2 may be responsible for the small ferroelectric polarization reported previously in this compound.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

New measurement of double- β decays of Mo 100 to excited states of Ru 100 with the CUPID-Mo experiment

The CUPID-Mo experiment, located at Laboratoire Souterrain de Modane (France), was a demonstrator experiment for CUPID. It consisted of an array of 20 Li 2 100 MoO 4 (LMO) calorimeters each equipped with a Ge light detector (LD) for particle identification. In this work, we present the result of a search for two-neutrino and neutrinoless double beta decays of 100 Mo to the first 0 + and 2 + excited states of 100 Ru using the full CUPID-Mo exposure (2.71 kg yr of LMO). We measure the half-life of 2νββ decay to the $0^+_1$ state as $T^{2ν→0^+_1}_{1/2}$ = (7.5 ± 0.8 (stat.) $^{+0.4}_{-0.3}$ (syst.)) × 10 20 yr. The bolometric technique enables measurement of the electron energies as well as the gamma rays from nuclear de-excitation and this allows us to set new limits on the two-neutrino decay to the $2^+_1$ state of $T^{2ν→2^+_1}_{1/2}$ > 4.4×10 21 yr (90% c.i.) and on the neutrinoless modes of $T^{0ν→2^+_1}_{1/2}$ > 2.1×10 23 yr (90% c.i.), $T^{0ν→0^+_1}_{1/2}$ > 1.2 × 10 23 yr (90% c.i.). Information on the electrons spectral shape is obtained which allows us to make the first comparison of the single state (SSD) and higher state (HSD) 2νββ decay models for the $0^+_1$ excited state of 100 Ru.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Solid-source metal-organic MBE for elemental Ir and Ru films

Thin films of elemental metals play a very important role in modern electronic nano-devices as conduction pathways, spacer layers, spin-current generators/detectors, and many other important functionalities. In this work, by exploiting the chemistry of solid metal-organic source precursors, we demonstrate the molecular beam epitaxy synthesis of elemental Ir and Ru metal thin films. The synthesis of these metals is enabled by thermodynamic and kinetic selection of the metal phase as the metal-organic precursor decomposes on the substrate surface. Film growth under different conditions was studied using a combination of in situ and ex situ structural and compositional characterization techniques. The critical role of substrate temperature, oxygen reactivity, and precursor flux in tuning film composition and quality is discussed in the context of precursor adsorption, decomposition, and crystal growth. Computed thermodynamics quantifies the driving force for metal or oxide formation as a function of synthesis conditions and changes in chemical potential. These results indicate that bulk thermodynamics are a plausible origin for the formation of Ir metal at low temperatures, while Ru metal formation is likely mediated by kinetics.

Materials Science↗
DOE OSTI2023

Advanced Fuel Cycle Cost Basis Report: Supporting Document 7 Presentation: Du and RU Disposal Costs [Slides]

Worldwide DU and RU in various chemical forms are some of the largest legacy products of the nuclear industry (defense & power) in both mass and volume. Chemical forms include U metal or alloy, UF6, UO2, UO3, U3O8, and UF4. Most of this material is now in above ground storage. Due to chemical stability and low water solubility oxides are the preferred form for safe storage and ultimate disposal. Long term U disposal in large amounts presents more of a potential radioactivity problem than its conversion and temporary storage. Now a near term problem with freshly-mined uranium ore, radon emanation will eventually be a long-term problem for both DU and RU dispositioned in large quantities at a specific location.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Water Formation Reaction under Interfacial Confinement: Al0.25Si0.75O2 on O-Ru(0001)

Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can change the reaction pathway of the water formation reaction (WFR) near room temperature when compared to the bare metal. In this work, we looked at the effect of doping the silicate with Al, resulting in a stoichiometry of Al0.25Si0.75O2. We investigated the kinetics of WFR at elevated H2 pressures and various temperatures under interfacial confinement using ambient pressure X-ray photoelectron spectroscopy. The apparent activation energy was lower than that on bare Ru(0001) but higher than that on the BL-silica/Ru(0001). The apparent reaction order with respect to H2 was also determined. The increased residence time of water at the surface, resulting from the presence of the BL-aluminosilicate (and its subsequent electrostatic stabilization), favors the so-called disproportionation reaction pathway (*H2O + *O ↔ 2 *OH), but with a higher energy barrier than for pure BL-silica.

36 MATERIALS SCIENCE↗
DOE OSTI2026

RU Net for Automatic Characterization of TRISO Fuel Cross Sections

TRistructural ISOtropic (TRISO) particle fuel is a type of nuclear fuel known for its high-temperature and high-burnup performance. Each sub-millimeter diameter TRISO particle consists of uranium-oxycarbide (UCO) or UO2 fuel kernel, coated with buffer, inner pyrolytic carbon (IPyC), silicon carbide (SiC), and outer pyrolytic carbon (OPyC) layers. The SiC layer acts as the main containment barrier for the TRISO particle to retain the fission products, while the IPyC and OPyC layers provide additional barriers to the release of fission products, especially fission gases. During irradiation, phenomena like kernel swelling, buffer densification, and IPyC fracture may impact fuel performance. Post-irradiation microscopy on entire compact cross sections or samples of individual particles deconsolidated from compacts is often used to identify these irradiation-induced changes in morphology. However, each fuel compact generally contains thousands of TRISO particles. To get statistical information on these phenomena, it is cumbersome work if done manually. For example, to get information about swelling/densification behaviors of different layers or kernels after irradiation, researchers previously manually measured the perimeter of each TRISO layer in hundreds of particles after four rounds of iterative grinding and polishing encompassing more than 2000 cross-section images for a total of four fuel compacts. To attempt to reduce the subjectivity inherent in that process and accelerate data analysis, we conducted a study on the automatic TRISO layer segmentation on cross-sectional microscopic images using Convolutional Neural Networks (CNNs). CNNs are a class of machine learning algorithms specifically designed for processing structured grid data that have gained popularity in recent years due to their remarkable performance in various computer vision tasks, including image classification, object detection, and image segmentation. In this research, we have generated the large irradiated TRISO layer dataset with more than 2000 cross-section TRISO microscopic images and the corresponding annotated images. Based on these annotated images, we have employed different CNNs for automatic segmentation of different TRISO layers. These include RU-Net (developed in this study), as well as three existing architectures: U-Net, Residual Network (ResNet), and Attention U-Net. The preliminary results show that the model based on RU-Net has the best performance in terms of intersection-over-union (IoU). Through the aid of these CNN models, we can expedite the analysis of TRISO particle cross-sections, significantly reducing the manual labor involved and improving the objectivity of the segmentation results.

Convolutional Neural Networks↗
DOE OSTI2020

Materials Data on Ru(SCl3)4 by Materials Project

RuSCl4(SCl2)3Cl2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four chlorine molecules, twelve sulfur dichloride molecules, and four RuSCl4 clusters. In each RuSCl4 cluster, Ru4+ is bonded in a distorted T-shaped geometry to three Cl1- atoms. There are a spread of Ru–Cl bond distances ranging from 2.37–2.42 Å. S2+ is bonded in a 2-coordinate geometry to two Cl1- atoms. There are one shorter (2.02 Å) and one longer (2.68 Å) S–Cl bond lengths. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Ru4+ atom. In the second Cl1- site, Cl1- is bonded in a distorted water-like geometry to one Ru4+ and one S2+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one S2+ atom. In the fourth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Ru4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ru(CO)4 by Materials Project

Ru(CO)4 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of forty-eight formaldehyde molecules and twelve ruthenium molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ru(CO)4 by Materials Project

Ru(CO)4 crystallizes in the orthorhombic Ibam space group. The structure is zero-dimensional and consists of sixteen formaldehyde molecules and four ruthenium molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Hydrogenolysis of n -eicosane over Ru-based catalysts in a continuous flow reactor

The hydrogenolysis of n-eicosane (C 20 H 42 ) was studied under differential conditions over Ru-based catalysts including Ru/SiO 2 , Ru/TiO 2 , and Ru/SBA-15, using a continuous flow reactor that was specially designed for large hydrocarbon reactants that are solids at room temperature. Similar rates and product distributions were obtained for Ru/SiO 2 and Ru/SBA-15 at 433 K, with the most abundant products being C 1 and C 19 hydrocarbons and smaller amounts of C 8 to C 18 also being produced. The higher yield of C 1 and C 19 indicates that cleavage of the terminal C-C bond is somewhat more facile than an internal C-C bond. At 473 K the product distribution shifted to mostly C 1 suggesting that, at this temperature, the adsorbed alkyl fragments undergo complete C-C bond scission prior to desorbing. Here, the conversion was also found to be inversely proportional to the H 2 pressure. Similar results were obtained for Ru/TiO 2 except this catalyst was found to be less active than both Ru/SiO 2 and Ru/SBA-15.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Ir–Ru Particles Enable Low-Loading Acidic Oxygen Evolution for Integrated Solar Devices

Integrated photoelectrochemical (PEC) devices for water splitting represent a compelling pathway for sustainable hydrogen production, directly converting solar energy into chemical fuels. While alkaline systems have achieved state-of-the-art solar-to-hydrogen (STH) efficiencies above 20% using earth-abundant catalysts, acidic PEC architectures provide unique advantages for compact device integration, fast proton transport, and stable operation under highly dynamic solar conditions. Proton-exchange membrane (PEM)-based configurations enable high current densities, low gas crossover, and rapid ionic response, making them especially well-suited for intermittent, bias-free PEC operation, despite alkaline electrolysis being more technologically mature. A critical limitation of acidic PEC systems remains, the oxygen evolution reaction (OER), which currently relies on scarce and costly iridium catalysts, restricting scalability. Here, in this study, we report a series of low-iridium mixed-metal oxide catalysts synthesized via a surfactant-assisted borohydride reduction method. An optimized Ir 0.5 Ru 0.5 O x catalyst exhibits exceptional intrinsic activity (>400 A g –1 Ir at 1.55 V vs RHE) in 0.1 M HClO 4 and maintains stable operation for over 10 days in an integrated PEC flow-cell. Sustained hydrogen production is achieved at 1.65 V with a total iridium loading of only 0.1 mg cm –2 , substantially below commercial PEM benchmarks. These results demonstrate a viable pathway toward scalable, high-performance acidic PEC hydrogen technologies.

Acidic electrolysis↗
DOE OSTI2022

Decreasing the Overpotential of Aprotic Li-CO 2 Batteries with the In-Plane Alloy Structure in Ultrathin 2D Ru-Based Nanosheets

We report the aprotic Li-CO 2 battery is emerging as a promising energy storage technology with the capability of CO 2 fixation and conversion. However, its practical applications are still impeded by the large overpotential. Herein, the general synthesis of a series of ultrathin 2D Ru-M (M = Co, Ni, and Cu) nanosheets by a facile one-pot solvothermal method is reported. As a proof-of-concept application, the representative RuCo nanosheets are used as the cathode catalysts for Li-CO 2 batteries, which demonstrate a low charge voltage of 3.74 V, a small overpotential of 0.94 V, and hence a high energy efficiency of 75%. Ex/in situ studies and density functional theory calculations reveal that the excellent catalytic performance of RuCo nanosheets originates from the enhanced adsorption toward Li and CO 2 during discharge as well as the elevated electron interaction with Li 2 CO 3 during charge by the in-plane RuCo alloy structure. This work indicates the feasibility of boosting the electrochemical performance of Li-CO 2 batteries by in-plane metal alloy sites of ultrathin 2D alloy nanomaterials.

25 ENERGY STORAGE↗
DOE OSTI2025

Thermodynamic Stability and Site‐Specific Distribution of Graphitic and Pyridinic Nitrogen in Graphene Moiré on Ru(0001)

Abstract Graphene‐like materials are of interest for large‐scale hydrogen storage applications due to their lightweight, durable, and scalable properties. Nitrogen‐doping minimizes kinetic limitations in diffusion and recombination on surfaces, however, the role of graphitic nitrogen (GN) and pyridinic nitrogen (PN) is not well understood. Nitrogen‐doped graphene is synthesized on Ru(0001) using chemical vapor deposition (CVD) of pyridine and ion irradiation. Scanning tunneling microscopy (STM), x‐ray photoelectron spectroscopy (XPS), and density functional theory (DFT) are used to identify the structure, location, and thermodynamic stability of nitrogen species within the graphene moiré. CVD of pyridine results in a low nitrogen concentration (<0.1at%), while the post‐growth nitrogen ion irradiation allows us to increase the concentration further. The concentration of GN and PN is controlled by varying the ion dose and annealing temperature. Comparison of measured and simulated STM images of GN and PN yield an excellent agreement, allowing us to confidently establish that GN is preferentially located near the center of the Atop region, while PN is located in the valley region of the graphene moiré. This report explicitly confirms the site assignments and provides a foundation for the site synthesis and analysis of structural and electronic properties that drive the reactivity of N‐doped graphene.

Gedara, Buddhika S. A. [Physical and Computational↗
DOE OSTI2021

Dual function materials (Ru+Na 2 O/Al 2 O 3 ) for direct air capture of CO 2 and in situ catalytic methanation: The impact of realistic ambient conditions

Here a dual function material (DFM) comprised of 1% Ru, 10% Na 2 O/γ–Al 2 O 3 was studied for combined direct air capture (DAC) of CO 2 and catalytic methanation in a temperature swing operation. In the newly proposed operation, the DFM captures CO 2 (400 ppm) from air at ambient conditions. The material is then heated in H 2 to a temperature sufficient for catalytic conversion of the captured CO 2 to renewable natural gas. In this study, we demonstrate high CO 2 adsorption capacity and rates at ambient conditions (25 °C); the adsorbed CO 2 is then successfully catalytically methanated upon heating in H 2 . Adsorption was also carried out in humid conditions, more closely simulating ambient air. Adsorption and methane production were greatly improved with stable initial performance. The rate of adsorption is shown to be flowrate-dependent, which is critical for future reactor design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Co 3 Ga 2 Ge 5 : Probing site mixing of the Ru 3 Sn 7 structure type with elements difficult to distinguish by diffraction

Co 3 Ga 2 Ge 5 was synthesized through arc-melting stoichiometric ratios of the elements, and a Ru 3 Sn 7 -type structure was confirmed by X-ray diffraction. Because Co 3 Ga 2 Ge 5 contains Ga and Ge, which have very similar X-ray and neutron scattering factors, any Ga/Ge crystallographic site preference cannot be determined with diffraction alone. The purpose of this study is to highlight the importance of using multiple techniques to characterize otherwise structurally ambiguous intermetallic compounds. Here, we utilize 71 Ga nuclear magnetic resonance spectroscopy and an analysis of the X-ray absorption fine structure to clarify the amount of Ga/Ge site mixing. Our combined use of X-ray diffraction and spectroscopy provides a comprehensive structural analysis of Ga site mixing across the Ge crystallographic sites, enhancing the understanding of the structure and properties of Co 3 Ga 2 Ge 5 .

36 MATERIALS SCIENCE↗
DOE OSTI2020

Cyano-ambivalence: Spectroscopy and photophysics of [Ru(diimine)(CN-BR 3 ) 4 ] 2- complexes

The UV–visible absorption and luminescence spectra of [Ru(diimine)(CN) 4 ] 2- derivatives have been tuned over wide ranges through variations in solvent, substituents on the diimine ligand, and boronation of the cyanide ligands. Here, trifluoromethyl substitution at the 4 and 4' positions of the diimine induces red shifts in metal-to-ligand charge-transfer (MLCT) absorption and luminescence bands. Boronation of the cyanide ligands produces substantial blue shifts in MLCT energies. The combination of diimine trifluoromethylation and cyanide boronation produces MLCT blue shifts that are about 75% as large as those produced by boronation alone.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗